Principal Characteristics of Cuban Neogene...
Transcript of Principal Characteristics of Cuban Neogene...
The American Association of Petroleum Geologists Bulletin
V. 53, No. 9 (September. 1969), P. 1938-1955. 13 Figs., 1 Table
Principal Characteristics of Cuban Neogene Stratigraphy'
MANUEL A. ITURRALDE-VINENT-
Lo Habana, Cuba
Abstract The Neogene (Miocene and Pliocene) rocks of Cuba occupy large areas of the is land. Those which over l ie the deformed Cretaceous eugeosyncl ine are described in this paper. Because most of Cuba is underla in by eugeosynci inal rocks, on ly a small part of the Neogene rocks is not descr ibed.
I d iv ide the Cuban Neogene rocks geographica l ly into five l i thofocies complexes. In a l l of the complexes, the strata ore pr inc ipal ly Miocene. Lithofocies complex I {Pinar de l Rfo Province) is a carbonate, sandstone-shale, and conglomerate sequence deposi ted in shal low neritic water. Lithofocies complex II (mainly Habana and Motanzas Provinces) is separated from complex I on the west and complex IV on the east by major nor th- t rending faults. The rocks are largely mar l , shale, and l imestone of deep-water deposi t ion and local nerit ic sandstone and l imestone. Lithofocies complex III (southern Isle of Pines) is a carbonate sequence of shallow nerit ic deposi t ion. Lithofocies complex IV (Las Vi l las, Camaguey, and western Oriente) consists mainly of carbonate and terrigenous-clastic rocks of shallow neritic deposi t ion. Lithofocies complex V (rest of Or iente Province) comprises a var ied group of conglomerate, sandstone, shale, mar l , l imestone, and dolomite beds deposi ted in diverse environments.
Tectonicolly, the Cuban Neogene rocks are div is ib le into (1) tronsgressive cover rocks (thin deposits, mainly carbonates, and general ly flat ly ing); (2) transgressive-regressive strata of subs id ing, deep basins (up to 1,000-1,500 m thick, var ied l i lhologic types, and dips as great as 40° ) ; and (3) tronsgressive deposits of shallow nerit ic basins (up to 600 m of carbonate and terrigenous-clastic rocks, d ips gent le , but locally as great as 20°).
The overol l Cuban Neogene history indicates gradua l shal lowing of the sea from earl iest Miocene through Pliocene t ime, and emergence of the island.
INTRODUCTION
The Neogene (Miocene-Pliocene) has been one of the least studied rock groups in Cuba, largely because its economic importance is very limited with regard to metallic mineral exploration; the principal economic use has been for construction materials and ornaments. Nevertheless, the Cuban Neogene is very important hydrologically, because the principal aquifers of potable water are in karst regions of the Neogene. Therefore, after the In-stituto Nacional de Recursos Hidraulicos (INRH=National Institute of Hydrologic Resources) was established, detailed studies were made of the principal hydrogeologic basins. The many new data discovered as a result of the studies permit new descriptions, and modi
fications of the information previously available on the Neogene strata.
This paper is not a summary of previously published results, but a presentation of INRH investigations in which I participated, either directly or indirectly, both in the field and in pa-leontologic studies in the laboratory.
Although they are less complete, many excellent works of a regional nature in the literature contribute 1o and complement the ideas expressed herein. Among them are contributions by Palmer and BermiJdez (1936), Brodermann (1945), Bermiidez (1950, 1961, 1967), Bermiidez and Hofstetter (1959), Bron-nimann and Rigassi ( 1963), Furrazola et al. (1964), Iturralde (1966, 1967a, 1968, and unpub. ms.), and Torre (1966).
Biostratigraphic Zonation
To acquaint the reader with the criteria used for dating Neogene strata, the concepts I developed for the Province of Matanzas (Iturralde, unpub. ms.) are summarized in Figure 1. The same concepts are applicable to all Cuba.
General Geology
The geology of Cuba has been described by Furrazola et al. (1964) and by Khudoley (1967). In general, Cuba consists of an ortho-geosynclinal sequence which extends the length
'Manuscript received, August 5, 1968; accepted, September 11, 1968.
- Instituto Nacional de Recursos Hidraulicos. The writer thanks A. A. Meyerhoff for translating
the original manuscript, and Pedro J. Bermudez and Frances Charlton de Rivero for checking the translation. The writer is grateful to the following persons for critical reading and review of the manuscript: Gustavo Furrazola-Bermudez, F.scuela de Ciencias Bio-logicas, Univ. de La Habana: Viasheslav V. Bamberg, Dpto. Ingenieria Geologica, Inst. Nac. Rec. Hidraulicos; Pedro .1. Bermiidez, Direccion de Geologia, Min-isterio de Minas e Hidrocarburos, Caracas; Frances Charlton de Rivero, Dpto. de Geologia, Univ. Central de Venezuela; and A. A. MeyerhoflE. The writer also thanks G. Z. Martashvili for data on the IVIoron basin, Kathryn L. Meyerhoft for drafting the illustrations, and Carol Thompson for typing the manuscript.
1938
Principal Characteristics of Cuban Neogene Stratigraphy 1939
of the island. A Late Jurassic-Cretaceous mio-geosynclinal facies occupies the north coastal region from northern Matanzas Province to northwestern Oriente Province (Fig. 2), and an age-equivalent eugeosynclinal sequence of volcanic rocks, graywacke, etc. underlies the rest of the island. Some metamorphic rocks are present on the Isle of Pines and in the Sierra de Trinidad, along the south coast of Cuba, as well as in southeastern Oriente Province. Fur-razola et al. (1964) and Khudoley (1967) interpreted most of the metamorphic rocks to be Early and Middle Jurassic. In northern Pinar del Rio Province, dated Early to Middle Jurassic strata are present. The evaporite diapirs of the north coast also contain Jurassic sediments (Ducloz, 1960; Meyerhoff and Hatten, 1968).
The orthogeosynclinal sequence was deformed strongly during Late Cretaceous and early Tertiary times. Middle Eocene and younger sediments gradually buried the relief that had been developed on the eugeosyncUnal rocks. The Neogene of Cuba is part of the younger, post-orthogeosynclinal sequence.
This paper concerns oiily the Neogene strata overlying the eugeosynclinal section (Fig. 2). Equivalent strata overlying the miogeosynclinal facies of the Cretaceous are not included, except those in the northern part of the Moron basin (Fig. 2). Hovrever, because much of Cuba is underlain by the eugeosynclinal facies, most Cuban Neogoie rocks are described. The only Neogene strata not described are those in the present offshore shelf areas, where lack of lithologic control makes descriptions impossible.
The Neogene is divfded into lithofacies complexes which are htsfsd on ^ e distinctive sedimentary rock suites and faunas present in different areas. Or(Hi{Hng the lithofacies associations into distinct complexes by region facilitates description and study. The boundaries between the complexes may be related in places to deep regional faults, and elsewhere to facies changes only (Fig. 2).
The following five principal lithofacies complexes are recognized above the area of the former eugeosynclTne from west to east.
Lithofacies complex 1.—Limited to Pinar del Rio Province. The eastern iliQwidary is the steep fault that extends from Martoi BJW to Carraguao Point (Fig. 2).
Lithofacies campltx ti.—'Extends from the Mariel-Carraguao faiUt to a f̂ uk joining Cirdenas and Cochi-nos Bays (Isle of FinWcmUded).
Lithofacies compltx III.—Developed on the south side of the Isle of Fines.
Lithofacies complex IV.—Bounded on the west by
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BANNER AND BLOW
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G L O B O R O T A L I A FOHSI LOBATA
G- FOHSI PERIPHEROACUTA & FOHSI P R A E F O H S I
G.PERIPHERORONDA
GLOBIGERINOIDES BISPHAERICUS G.ALTIAPERTURUS
CATAPSIDRAX
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P L A N U L I N A
EDWARDSIANA
C A N I M A R E N S I S
SORITM D A E -
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S O R I T I I D A E -M I O G Y P S I N A
L E P I D O C r C L I N A -
HETEROSTEGINA-
MIOGYPSINA
KLM
FIG. 1.—Foraminiferal zonation of Neogene rocks of Cuba. Neogene as used herein includes Aquitanian stage.
lithofacies complex II, and on the east by a line extending from Gibara to the Gulf of Guacanayabo.
Lithofacies complex V.—Occupies the region southeast of complex IV.
This subdivision of the areas of Neogene deposition is purely informal and is used only to simplify the treatment in the text.
STRATIGRAPHY
In the descriptions of the five lithofacies complexes, formation names are used only if they are easily recognized. Where there is doubt I propose a new name or do not refer to specific "formations." The stratigraphic extent of certain formations has been modified; hence the sections presented differ somewhat from those of previous workers. To make correlations as precise as possible, the lithologic units described herein have been referred to known formations. Thus the nomenclature has been kept relatively simple.
Lithofacies Complex I Lithofacies complex I (Fig. 2) occupies
most of Pinar del Rio Province south of the Sierra del Rosario and Sierra de los Organos,
FIG. 2.- Index map of Cuba showing principal geologic features, geographic localities, and Neogene lithofacies complexes dicussed in text. Salt-dome localities from Ducloz (1960) and Meyerhoff and Hatten (1968).
Principal Characteristics of Cuban Neogene Stratigraphy 1941
and west of the steep fault between Mariel Bay and Carraguao Point. Movement along the fault raised the region occupied by this lithofa-cies complex. As a result, the sediments were deposited exclusively in a neritic environment.
According to the structure of this region, this complex must be divided into two subcom-plexes: (1) the Palacios basin, and (2) the San Diego de los Baiios tectonic unit (Khudoley. 1967).
Subcomplex 1.—This is a deeply subsided basin where early to middle Miocene sediments were deposited; the thickness is more than 1,000 m.
The sequence consists of a basal terrigenous-clastic unit and an upper calcareous unit. The basal part is polymictic conglomerate, with poorly sorted clasts ranging from very small to 0.5 m in diameter. The matrix either is calcareous cement or consists of smaller grains of gravel size. The biocoenosis is predominantly algae, moUusks, miliolids, Archaias an-gulatus, Miogypsina sp., Heterostegina sp., and Lepidocyclina sp., which correlate the unit with the Lepidocyclina-Heterostegina-Miogyp-sina zone of the early Miocene (Fig. 1). The thickness is varied and the maximum is 200 m. The clastic unit is discordant on older rocks, but grades upward into a calcareous unit 300-700 m thick containing, near the middle, a 50-300-m-thick terrigenous-clastic section. The basal terrigenous clastic unit grades laterally southward into sandy limestone, conglomerate with smaller clasts, and sandy calcareous shale that rest conformably on the Oligocene. The total Neogene section changes in thickness laterally, and toward the west neither the basal conglomeratic unit nor the upper terrigenous-clastic section is present. The absence of the two units in the west may have been caused by topographic relief which affected the basin at the time of deposition.
The carbonate rocks of the upper sequence consist of organogenic detrital limestone and sandy limestone. A few argillaceous limestone beds are present. Westward, where terrigenous beds are absent, the upper section consists of dolomite and dolomitized limestone (Lapshin cfa/., 1968).
Both limestone sections contain the following biocoenosis: Kuphus incrassatus, Pecten sp., Orthaulax sp., Amphistegina angulata, Gypsina sp., Archaias angulatus, Textularia sp., miliolids, and algae. In the lower carbonate units, the following additional forms are present: Miogypsina sp., Valvulainmina sp.. Sorites
sp., and Amphisorus sp. The terrigenous-clastic section between the
two limestone sections consists of silica-cemented sandstone and shale; the amount of shale increases southward. In the shale, the following fauna is found: Ammonia beccarii sobrina, A. beccarii parkinsoniana. Elphidium lens, E. lani-eri, Nonion sp., Globoroialia menardii, Miogypsina sp., and ostracods. The sandstone generally is barren of fossils.
In age, the upper carbonate-terrigenous-clastic unit can be considered equivalent to the MiogypsinaSor'ituddt and Soritiidae-Milioli-dae-Amphisteginidae zone of the early to middle Miocene.
The entire sequence dips southward, and the dip steepens to 30-40° at its north limit. The strata generally are folded gently. The sequence probably correlates with the GUines Formation and the Arabos Member of that formation, contrary to Bermudez's (1950) opinion. Bermiidez proposed the name "Paso Real Formation" for these rocks (Fig. 3; Itur-ralde, 1967a).
Subcomplex 2.—This subcomplex is predominantly carbonate. The sediments attain a thickness of 800 m and, depending on the ages present, correspond to the Soritiidae-Miliolidae-Amphisteginidae zone of the lower to middle Miocene. Aquitanian strata are absent. The area where this subcomplex is present coincides with an upfaulted block (Furrazola et at., 1964, their Fig. 88). The sequence is composed of organogenic and dolomitized limestone with beds of fine-grained sandstone and shale. The fauna is homogeneous throughout, and contains Archaias angulatus, PeneropUs proteus. P. planatus, CyclorhicuUna voinpressa, miliolids, Amphistegina spp. and, in the brackish-water beds, also Elphidium sagrai, Ammonia beccarii parkinsoniana, and ostracods.
The northern fringe of the Neogene strata, which occupies a narrow zone around Mariel, consists of organogenic and organogenic-detri-tal limestones of early Miocene age (Iturralde, 1967b).
As indicated by the fauna and lithologic character of lithofacies complex I, the sediments originally were deposited in water no deeper than 100 m. Most of the deposits were laid down near the coast. Ultimately, an influx of fresh water modified the conditions of deposition, and sand and clay of the upper terrigenous-clastic unit were deposited. Deposition ended with the upper marine carbonate sequence.
1942 Manuel A. Iturralde-Vinent
CRET
SECTION A
FIG. 3.—Schematic north-south cross section of Neogene, southern Pinar del Rio Province, hthofacies complex I. /, conglomerate; 2, limestone; 3, sandstone; 4, shale. Not to scale. Modified from Nicolaev (1968) and Urusova and Balabanova (1966). Length of cross section is approximately 18 km. Location on Figure 2.
Lithofacies Complex II
Lithofacies complex II (Fig. 2) represents a peculiar set of environmental and depositional conditions, because it was deposited in a deep basin bounded by steep faults. The basin had the characteristics of a graben. For convenience, the sequence is described by ages, from oldest to youngest (Fig. 4 ) .
Early Miocene.—The early Miocene sediments were deposited predominantly in a marine pelagic environment, although along the margins of the pre-Neogene structures of the orthogeosyncline, the sediments were deposited in shallower neritic water. The pelagic strata have been referred to the Jaruco and Cojimar Formations, whereas the neritic facies has been referred to the Husillo ( = Colon) and Giiines Formations. The pelagic sequence extends from the base of the Catapsidrax dissimilis zone to the top of the Glohorotalia fohsi lohata zone, and the neritic sequence includes the Lepido-cyclina-Heterostegina-Miogypsina, Miogypsina-Soritiidae, and Soritiidae-Miliolidae-Amphis-teginidae zones (Fig. 1).
The Jaruco and Cojimar strata consist of calcareous to shaly organogenic marl, argillaceous limestone, calcareous sandstone, and shale, generally in beds 20-50 cm thick. The biocoenosis of the two formations consists of planktonic and small benthonic foraminifers, together with moUusks, ostracods, and echino-derms in the part corresponding to the Cojimar. In the part corresponding to the Jaruco, planktonic and small benthonic foraminifers predominate.
The forms most typical of the zones of the early Miocene pelagic beds are Glohorotalia obesa, G. mayeri, G. peripheroronda, G. prae-menardii, G. archeomenardii, G. fohsi prae-fohsi, G. fohsi peripheroacuta, G. fohsi lohata, Globigerinella aequilateralis, Orhulina uni-versa, O. suturalis, Globoquadrina venezuel-
ana, G. altispira, G. tripartita rohri, G. de-hiscens, Globigerinoides quadrilobatus, G. trilo-bus, G. sacculifer, G. ruber, G. inmaturus, G. hisphaericus, G. altiaperturus, Catapsidrax dissimilis, Globigerina praebulloides s.s., G. con-cinnas S.I., "Sphaeroidinella" grimsdalei, "S." de-hiscens, and others.
The thickness of the strata is varied, but averages about 200 m. The dip generally does not exceed 20-25°, but the range can be from 0 to 40°. The biocoenosis indicates deposition in water of normal salinity, ranging in depth from 100 m to more than 300 m.
The rocks which are equivalent to the Giiines and Husillo (— Colon) Formations are adjacent to and on ancient topographic highs of orthogeosynclinal rocks. The strata consist of argillaceous organogenic limestone, organo-genic-detrital limestone, dolomite, and sandstone. The thickness ranges from 50 to 100 m, and the dip does not exceed 30°. Though generally massive, beds in places are 30-40 cm thick.
The biocoenosis of these strata of Aquitan-ian-Burdigalian age is characteristic of shallow normal-marine water, and consists of large benthonic foraminifers. corals, moUusks, echino-derms, and other forms. Among those identified are Lepidocycliiia undosa, L. favosa, Heteroste-gina antillea, Nuinmulites dius, Miogypsina an-tillea, Amphistegina angulala, and A. rotundata.
Middle Miocene.—-Rocks of this age are widely distributed in the zone of lithofacies complex II and are found in numerous outcrops. They generally are correlated with the Giiines Formation and the Arabos Member of that formation. The oldest strata extend into the upper part ol the early Miocene (G. fohsi rohusta zone of Bolli. 1957). The fauna shows that most of the unit is equivalent to the upper part of the .Soritiidae-Miliolidae-Amphistegi-nidae zone. In places, the middle Miocene is separated from (he lower Miocene bv a slight
Principal Characteristics of Cuban Neogene Stratigraphy 1943
discordance caused by syndepositional movements. Where slight discordances are present, they are disconformities characterized by an abrupt lithofacies change. In other places the contact is gradational. There is no proof of a hiatus between the early and middle Miocene beds. In a very few localities, some strata of probable middle Miocene age overlap the lower Miocene and are on pre-Miocene rocks.
The lithofacies are extremely variable both laterally and vertically, although dolomite is found on both the east and west. Dolomite predominates in the upper part of the western section, whereas it predominates in the lower part of the eastern section. The dolomite seems to be of secondary origin, and the fact that dolomite is present both on the east and the west does not hinder a reconstruction of the various fades.
The Giiines Formation, properly defined and excluding the Arabos Member, consists of or-ganogenic-detrital, relict-organogenic, coralline, biohermal, shaly, recrystallized, and dolomi-tized limestone beds, calcareous sandstone, dolomite, and calcareous marl. The Arabos Member consists of calcareous shale, marl, and sandstone which form lenses of varied thickness within the carbonate rocks. The various lenses of the Arabos Member seem unlikely to be of the same age, because they represent responses to changing depositional conditions in different localities.
The middle Miocene rocks range in thickness from 100 to 400 m, but locally may be thicker or thinner. The general dip range is from 0 to 10°, and the beds are folded gently within the outcrop area.
On the Zapata Peninsula, southern Matanzas Province, the El Maiz test well was drilled to a total depth of 610 m (Fig. 5 ) . Below 440-450 m, the well penetrated a section of limestone, shaly limestone, and calcareous shale bearing a fauna which corresponds to that of the lower part of Banner and Blow's (1965, 1967) zone No. 16. This sequence indicates a very marked lateral facies change between rocks of this area and the equivalent rocks on the north. TTie rocks found in the El Maiz well do not belong to the Giiines Formation. 1 have named this section the "El Maiz Formation," of middle to late Miocene age (Iturralde. unpub. ms.). The biocoenosis corresponding to the middle Miocene consists of mollusks, algae. and planktonic and small benthonic foraminif ers. Significant species include Giohorotatia inero-tumida, G. pseudomiocenica, Glohigerina eggeri, Orbulina universa/'Sphaeroidincllci" xeminulina,
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1944 Manuel A. Iturralde-Vinent
Globigerinoides trilobus, G. ruber, and Globo-quadrina altispira. These particular species were found in a core at a depth of 526-539 m. There is no question but that the sequence represents a lateral facies change of the Giiines. Geographically, the El Maiz facies is present in the Zapata Peninsula west of Cochinos Bay (Bay of Pigs).
Late Miocene.—Late Miocene strata are restricted in lithofacies complex II to the Zapata Peninsula, and to a 1-2-km-wide northern coastal fringe zone between the cities of Matanzas and Cardenas, Matanzas Province (Fig. 4 ) . They have been studied in the El Maiz well (Fig. 5) on the Zapata Peninsula, but the only data from the north coast of Matanzas Province are field observations. I include the late Miocene in the El Maiz Formation of the Zapata Peninsula, but use the informal term "Gypsina beds" for the north coast outcrops (Iturralde, unpub. ms.).
On the Zapata Peninsula, the upper Miocene rocks consist of shaly limestone and calcareous shale. The fauna, composed almost wholly of planktonic and small benthonic foraminifers (Table 1), permit correlation with zones Nos. 16, 17, and 18 of Banner and Blow (1965, 1967). The total thickness on the Zapata Peninsula is about 280 m, and the water depth at the time of deposition was 150-200 m.
Rocks of equivalent age along the north
coast of Matanzas do not appear to be thicker than 100 m. They are composed of calcarenite beds which grade laterally into sandy marl and limestone. The biocoenosis consists of mollusks, ostracods, foraminifers, echinoderms, brachio-pods, and other marine forms. The only sample containing an age-diagnostic fauna was reported by Bermudez (1967). I collected two samples which contain unidentifiable planktonic foraminifers and the following ostracods, identified bv W. A. van den Bold: Paracypris sp., Bairdia longisetosa. B. antillea, B. spp., Quadracytfiere producta, Mutilus confragosiis, Xestoleberis sp., Paracytheroma sp., Cytixerella sp., Loxoconcha dorsotuhercidata. The samples were collected below the Homicultura Hospital, Matanzas City, in outcrops which Ber-miidez (1967) assigned to the upper Miocene.
Along the Rio Canimar, the strata dip 6°; in other areas they dip as much as 10° or more. The strata were deposited in a marine environment, possibly near the coast, and the waters became muddy as a result of the influx of terrigenous materials from nearby rivers.
Pliocene.—Rocks of Pliocene age have been identified from planktonic foraminifers along the northern coast of Matanzas Province. The strata identified are late Pliocene. Pliocene rocks in the south are found only on the Zapata Peninsula. The\ contain a benthonic
Table 1. Microfauna Identified from Banner and Blow's (1965,1967) Zones 16-18, EI Maiz Boreliole, Zapata Peninsula.*
/ EL M A I Z BOREHOLE
Z A P A T A P E N I N S U L A , L A S V I L L A S
GLOBOROTAL IA WEROTUMIDA
& L O B O R O T A L I A P L E S I O T U M I D A
GLOBOROTAL IA P S E U D O M I O C E N IC A
G L O B O R O T A L I A M U L T I C A U E RATA
G L O B O R O T A L I A SR A
G L O B O R O T A L I A SR B
G L O B I G E R I N A EGGERI (=G. OUTER TREI )
H A S T I G E R I N A P E L A G I C A
O R B U L I N A J N I V E R S A
" S P H A E R O I D I N E L L A " S E M I N U L I N A
" S P H A E R O I D I N E L L A " S E M I N U L I N A KOCKI
" S P H A E R O I D I N E L L A " D E H I S C E N S
G L O B I G E R I N O I D E S RUBER
G L O B I G E R I N O I D E S T R I L O B U S
G L O B I G E R I N O I D E S I M M A T U R U S
G L O B I G E R I N O I D E S O B L I Q U U S
G L O B I G E R I N O I D E S C O N G L O B A T U S
G L O B O Q U A D R I N A A L T I S P I R A
G L O B O Q U A D R I N A CF. VE N E Z U E LA N A
" S P H A E R O I D I N E L L O I D E S " S U B D E H I S G E N S
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Principal Characteristics of Cuban Neogene Stratigraphy 1945
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FIG. 7.—Stratigraphic section exposed at Abra of Rio Yumuri, .Matanzas Province. Vertical scale ill meters. Ixication on Figure 2. Symbols same as for Figure 5.
fauna which is not diagnostic, and the exact age cannot be ascertained.
In the nor thern par t of the province, the sequence occupies par t of a nar row coastal belt between Matanzas City and Cardenas . It
near Ceiba Mocha. The Pliocene consists of organogenic, argillaceous, and sandy limestone, sandy marl , shale, sand, gravel, and conglomerate . These lithologic types were penetrated in test well N o . 28, drilled at the con-
extends into the Rio San Agustin basin to fluence of the Ri'os Canas and .San Agustin
1946 Manuel A. Iturralde-Vinent
(Fig. 6) . The thickness in the well is 80 m. The fauna includes Globorotalia tosaensis, G. hirsuta, G. acostaensis humerosa, and Globi-gerinoides ruber pyramidalis.
A very well-exposed section of Pliocene crops out at the Abra ("gateway") of the Rio Yumurl (Fig. 7 ) . The beds dip 6° S 30°E. The section is composed of 80 m of polymictic conglomerate and sandstone, calcarenite, and biohermal limestone, in medium to thin beds. The section appears to be partly deltaic. The biocoenosis includes mollusks, foraminifers, bryozoans, corals, ostracods, phanerogam leaves, and other fossils. The deposits appear to have formed at a river mouth where marine and estuarine conditions alternated.
Bermiidez (1967) described from the Rio Canimar a typical fauna of Pliocene age. The sequence there consists of calcarenite and limestone beds which dip 6° seaward. The term Canimar Formation is used for the Pliocene in that area, and the facies in the Abra of the Rio Yumuri and in the Rio San Agustin basin are referred to the El Abra Member of the Canimar Formation.
The Pliocene of Zapata Peninsula consists of possibly 150 m of organogenic limestone which was penetrated in the El Maiz well (Fig. 5) . I have termed this Pliocene unit the "Peninsula Formation" (Iturralde, unpub. ms.).
Lithofacies Complex III
Lithofacies complex III (Fig. 2) has been described by Kuman and Gavilan (1965), and is not described in detail here. The data in the INRH files are incomplete, and come from a few boreholes drilled by INRH in the southern part of the Isle of Pines. The rocks consist of 400 m, or less, of organogenic and organo-genic-detrital limestone, with a fauna similar to that of the Giiines Formation.
Lithofacies Complex I \
This is the most extensive of the lithofacies complexes (Fig. 2) and is the most uniform in
thickness and lithologic character. The area which it covers is bounded on the west by lithofacies complex 11 and on the east by a a line joining Gibara Bay on the north coast with the Gulf of Guacanayabo on the south coast. The complex can be divided conveniently into three subcomple.\es: (1) the western region (Matanzas Province), (2) the southern part of the Sierra ilc Guamuhaya (Trinidad), and (3) the easicin region, including the Moron basin.
The complex consists predominantly of a carbonate and terrestrial-clastic facies deposited in a shallow neritic environment (Fig. 8). The rocks are mainK of early and middle Miocene ages, and in vers tew places are thicker than 500 m. They have been referred to the Colon and Giiines [''urniations.
Suhcoiitph'x I. Ihe lower part of the section in the western region consists of calcareous organogenic marl, somewhat argillaceous or-ganogenic-detnlal limestone, and thin lenses of sandstone. Ihe fauna includes mollusks. ostracods. brvozoans, and large benthonic foraminifers which are correlated with the Lepidocyclina-H eterostegina-M iogypsina zone of the early Miocene. The most typical species of the assemblage are Lcpidocyclina undosa, L. favosa. L. xiinuigHiwnsis. Miogypsina aiilil-lea, Hetcrosteiiina diUiUcu. and Niiniinidites diiix. Dip is no greater than 15°, and the thickness does not exceed 100 m. The unit is correlated with the Colon ( = Husillo) Formation. The depth of water in which the sediments were deposited was not greater than 150 m. Gener.ilK, salinitv was normal, and the water was slighth muddy.
Underlying these beds in places is a conglomerate unit about 20 m thick. It is polymictic conglomerate with a calcareous matrix in the upper part and a clay or sandy matrix in the lower. Clasls range in diameter from I mm to 3 cm or more, and are angular to sub-rotinded. No fossils have been found, but the a"e is assumed to he oarlv Miocene.
S E C T I O N C
FIG. 8.—Schematic north-south cross section of Neogenc rocks of lithofacies coinplex IV, Matan/.as and I.cis Villas Provinces. J, Colon Formation; 2, Gtiines Formation; and 3, .Arabos Member of Guines Formation. Not to scale. Subcomplex 2 is at southeastern side of section (Banao and Giiines Formations). Length of cross section is approximately 80 km. Location on Figure 2. } , = Upper Jurassic. Olher symbols snine as on Figure 10.
Principal Characteristics of Cuban Neogene Stratigraphy 1947
Above this sequence the Giiines Formation was deposited. Its lithologic character and fauna are the same as lithofacies complex II. The Arabos Member is well developed, reaching a thickness of 100 m (Iturralde, 1966). Silicified sandstone in the Arabos is scarce in this area. The total thickness of the GiJines, except in very few places, does not exceed 300 m and is more commonly 100-150 m. The strata are gently folded; maximum dips are 10-15°.
Subcomplex 2.—In subcomplex 2, south of the Sierra de Trinidad along the south coast, basal conglomerate is present, as in Pinar del Rio Province. As would be expected, the conglomerate differs in composition from that of Pinar del Rio—in content, type of cement, and thickness—although the conglomerates are of similar genetic origin. Microfaunal and field evidence indicates a late Oligoccne to early
METERS I . -
KLM
FIG. 9.—Type section of Banao Formation, Loma Maria Teresa, near Rio Higuanojo, soutli of Sierra de Trinidad, Las Villas Province. Vertical scale in meters. Location on Figure 2. Symbols same as for Figure X.
Miocene age {Lepidocyclina-Heterostegina-Miogypsina zone). The basal conglomerate underlies the Giiines Formation.
1 propose the name Banao Formation for the conglomerate unit below the Giiines Formation. The fauna consists of Lepidocyclina yurnagunensis morganopsis, L. duclozi. L. un-dosa, L. favosa, L. wayland-vaughani, Gypsina sp.. Miogypsina sp., miliolids, algae, corals, and other forms. The type section at Loma Maria Teresa, near the Rio Higuanojo (Fig. 9; Lambert coordinates N-536, E-217.6), uncon-formably overlies severely deformed schist. From top to base the following section is present.
Thickness {M) Descriptiiin
(.iJlNES FORMATION
10. Limestone, organogenic-detrital, compact, recrystalli/ed, eL|uivalent to basal Giiines .35
Total Giiines, this iocalitv 'SS
BANAO FORMAriON (conglomerate unit) 9. Limestone, organogenic-detrital 10 8. Conglomerate, polymictic, calcite cement
containing clasts ranging in diameter from a few millimeters to 20-30 cm; clasts are both angulai and loiinded 10
7. Sandstone 4 6. Conglomerate as above 10 ."i. Limestone, compact, organogenic-detrital 0.3 4. Conglomerate, polymictic 3 3. Limestone, sandy, compact 3 2. Conglomerate, conipaci; interbedded with
limestone, ..onipact, beige; inlergrada-tional . , 3
1. Marl, light-brown, sandy, with clasts of underlying schisl 2
Total eongloiiieiate iinii 45.3
Angular nnconfonin'ly
Schist —
The strata at the type locaUty dip 25° east-northeast. The basal Guines and Banao Formations in this locality are Miocene, and are part of the LepidocycUna-Heterostegina-Miogypsina zone. The biocoenosis is composed of large for-aminifers characteristic of the zone, but mixed with reworked faunas from older rocks.
The conglomerate crops out at other places along the highway between Banao and Trinidad, where it dips 10-12° east-northeast. Although the thickness was not measured along the highway, it is estimated to be 80 m. In the section between Banao and Trinidad, the conglomerate directly overlies the schist or late Eocene marl, and lenticular beds of late Oligocene marl are included in the upper part of the con-silomerate.
1948 Manuel A. Iturralde-Vinent
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FIG. 10.—Neogene section penetrated in water well, Vertientes, southern Camagiiey Province. Lithofacies complex IV. Check marks in unit at base represent Cretaceous volcanic rocks of eugeosyncline. Vertical scale in meters. Location on Figure 2. Symbols same as for Figure 8.
Above the conglomerate beds of the Banao Formation, in areas other than Loma Maria Teresa, is 200 m of the Giiines Formation. This unit consists of organogenic recrystallized limestone containing lenses of sandstone and shale. The microfauna is composed of Miogypsina sp., Gypsina globulus, Amphistegina angulata, Archaias angulatus, Cyclorhiculina compressa, miliolids, globigerinids, and ostracods. Mollusks also are present. The assemblage corresponds in age to the Miogypsina-Sorit'iidae zone of the early Miocene.
The 200-m-thick Giiines unit is overlain by 150-200 m of generally massive, organogenic limestone, shaly limestone, marl, and a few beds of limestone and dolomite. The fauna is younger than that of the Giiines, and consists of elements of the Soritiidae-Miliolidae-Ani-phisteginidae zone, such as Textularia aggluti-nans, Asterigerina carinata, Pyrgo denticulata, and Elphidium sagra. These forms are not common in rocks of middle Miocene age. Therefore, this section is assigned only tentatively to the Guines.
The entire section dips slightly toward the sea, and is gently folded.
Subcomplex 3.—The eastern region of lithofacies complex IV generally is characterized by
a lower section of marl and shale (Arabos Member) and an upper section of limestone of the Giiines Formation proper. In a borehole drilled at Vertientes. sotithern Camagiiey Province (Fig. 10), the lower beds of this sequence include siltstone, shale, and marl, with a fauna typical of the Arabos Member. The upper part contains limestone characteristic of the Giiines Formation. In age the sequence is equivalent to the Soritiidae-Miliolidae-Amphisteginidae zone of the early and middle Miocene, as is shown by the presence of Procythereis cf. defonnis and, higher in the section, of Globorotalia menardii.
A more complete section is north of Victoria de las Tunas, western Oriente Province (Fig. 11). The lower part consists of calcareous shale, marl, shaly limestone, thin lenses of gypsum, lignite, and beds with plant remains. The marl and argillaceous limestone are more abundant above, whereas shale is more common below. Pyrite and pyritized materials are common in the samples. The biocoenosis consists predominantly of small foraminifers and ostracods typical of waters of less-than-normal salinity. However, in places, fragmented remains of mollusks, echinoderms, and other forms are present. In many zones one or two species of Foraminifera may dominate the fauna.
In the Victoria de las Tunas section, the most common forms are Ammonia beccarii s.l., A. beccarii parkinsoniana, Elphidium lens, E. chipolensis, Discorhis cercadensis, D. cf. flori-densis, Nonion sp., Peneroplis sp., Archaias sp., Gypsina sp., Amphistegina angulata, Clavulina tricarinata, Valvulamnuna sp., Hastigerina? sp., Glohigerina concinna angustiumhilicata, miliolids, and ostracods. W. A. van den Bold identified the following ostracods from three samples in the lower part of the sequence: Bairdia witli-sensis, B. condylus, B. antillea, B. spp., Triehe-lina crumena, Haplocytheridea .nephensoni, H. cubensis, H. suhovaiu, H. cf. pinguis, Cush-manidea howei, Aurila galerita, A. amygdala, Procythereis cf. deionnis, Quadracythere antillea, Jugosocythcre vicksburgensis, Loxoconcha antillea, L. sp.. I'aracythcridea tschoppi, Cythe-rura cf. sella, Xestoleheris dactylotypa, X. sp., Macrocypris cf. decora, Actiiiocythere hahamen-sis, Munseyella sp., f'aracypris sp., Cytherella sp., and Perissocythendea sp.
Boreholes have drilled to 130 m, but have not penetrated the complete section. The age may be considered lo be early Miocene, though index fossils are laekint; and the rocks may be
Principal Characteristics of Cuban Neogene Stratigraphy 1949
SECTION E
FIG. 11.—Schematic north-south cross section of Neogene rocks of lithofacies complex IV, north of Victoria de las Tunas, western Oriente Province. 7, limestone; 2, marl; 3, shale; and 4. lens oi carbonized plants. Cr̂ =• Cretaceous volcanic rocks of eugeosyncline; Z Cr^ = ultramafic rocks. Not to scale. Modified from Kusmin and Borodin (1967). Length of section is approximately ?,S km. Location on Fi^ure 2.
of middle Miocene age at the top. In my opinion, the section is equivalent to the Arabos Member of the Giiines Formation; its lithologic character, fauna, and apparent mode of origin support this interpretation.
Above these beds is 80 m of organogenic-de-trital limestone, in places dolomitized and locally argillaceous, of middle Miocene age.
The Moron basin in northwestern Camagiiey Province (Fig. 2) contains a Neogene sequence which also can be included within subcomplex 3. The basin was named by Meyerhoff and Hatten (1968), who described its strata under the heading of Unit 1 (p. 342). However, I obtained most of the information given herein from G. Z. Martashvili (personal commun.).
The lower part of the Moron basin section corresponds to the Arabos Member of the Giiines Formation. It consists of bluish, calcareous shale with fine flakes of gypsum, and intercalated beds 50-60 cm thick of gypsum and calcite. These strata grade upward into compact, calcareous marl with fine-grained, noncalcareous sandstone beds in the lower
part and limestone and dolomite beds in the upper part. The total thickness of the shale-marl complex is approximately 170 m.
Conformably overlying the shale-marl sequence is compact, massive-bedded, finely crystalline, dolomitized limestone with a few beds of dolomite and intercalations of marl. Toward the northern pari of the basin, the limestone complex is thicker than 300 m. The unit corresponds to the Giiines Formation (sensu stricto). A cross section of the Moron basin is presented on Figure 12. Meyerhoff and Hatten (1968) noted that the total thickness of the Neogene ranges from ZZ."! to .'̂ 40 m in the basin.
The Neogene section in the basin lies with erosional unconformity on Paleogene, Cretaceous, and igneous rocks. It is almost horizontal, though some gentle folding is apparent; the broad, gentle folds generally trend northwest-southeast, and dips are toward the southwest or northeast. The age of the strata is early and middle Miocene, although the basal part of the Aquitanian has not been identified.
Locally the Moron basin sequence overlies
CIEGO
j ; / ^ V V CR2 V V
V V
SECTION D
/ V' V \
v J
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-300 M
FIG. 12.—Schematic south-north cross section of Neogene rocks of lithofacies complex IV, subcomplex 3, Ciego de Avila to Moron, northern Camagiiey Province. Modified from G. Z. Martashvili (personal commun.). Approximately 45 km from south to north. Figure 2 shows location. 7, marl; 2. clayey limestone; 3, dolomite and dolomitic limestone; 4, claystone. Cr„ :^ Lower Cretaceous: Pg. Focenc; N,' lovvcr Miocene: N,"- - middle Miocene; Q = Quaternary.
1950 Manuel A. Iturralde-Vinent
with slight angular unconformity a section of calcareous marl that is similar lithologically and faunistically to the Colon Formation, but neither Miogypsina nor Soritiidae is present. The absence of this fauna leads me to believe that the calcareous marl below the Arabos Member is Oligocene. If so, it is not equivalent to the Colon; and if the Colon is absent in the Moron basin, the basin belongs in subcomplex 3. If future studies show that the calcareous marl complex is early Miocene, the Moron basin section should be assigned to subcomplex 1.
Lithofacies Complex V
Lithofacies complex V, limited to Oriente Province, is characterized by marked, abrupt lateral and vertical lithofacies changes. The western limit is the eastern border of lithofacies complex IV. Because of its great variability, it is neither possible nor reasonable to characterize this complex as a whole. Instead, it is best to consider separately the three subcomplexes into which is may be divided. According to the facies and tectonic characteristics, the three subcomplexes are (1) Cauto basin, (2) Nipe basin, and (3) Guantanamo basin and the surrounding area.
Subcomplex 1.—Subcomplex 1 occupies the Cauto basin (Fig. 2) , which contains a very thick section of Tertiary and older rocks. INRH studies began there only recently and data are sparse. Several wells along the northern margin of the basin penetrated lower Miocene rocks (Lepidocyclina-Heteroslegina-Miogypsina zone). The fauna consists of Amphistegina angulata, A. rotundata, Nurn-mulites dius, Lepidocyclina sp., Miogypsina antillea, Peneroplis sp., Archaias sp.. Prucy-thereis cf. deformis, miliolids, and other forms. The strata are limestone, argillaceous limestone, shale, and marl; the thickness is unknown.
Other wells in the same region penetrated limestone and calcareous shale of the Miogyp-.v/«a-Soritiidae zone containing Miogypsina sp., Archaias sp., Amphistegina angulata, A. rotundata, ostracods, and other species. Above this sequence are marl and shale with Elphidium sp., E. chipolensis, Clavulina tricarinala, Ammonia heccarii parkinsoniana, Discorhis sp., Procythereis cf. deformis, Bairdia sp., miliolids, and other fossils.
Because of the scanty data from the subcomplex, samples were utilized from two wells (Fig.
2) drilled during the late 1950s by United States petroleum companies.' Data were furnished through the courtesy of Gustavo Furrazola-Bermildez. The Lavanderas No. 1 (just offshore in the Gulf of Guacanayabo) and Manzanillo No. 1 (near the town of that name) boreholes penetrated total thicknesses of 1,100 and 700 m, respectively, of the Neogene. Lavanderas No. 1 found a section of shale and limestone, at the base of which is a shale intercalation containing a pelagic microfauna. In Manzanillo No. 1, lower Miocene calcareous marl, shale, dolomitized limestone, sandy limestone, sandstone, and conglomerate were penetrated. The fauna includes specimens of Orbulina sp., Globigerina spp., Globorotalia menardii, G. praemcnardii, Miogypsina sp., Heterostegina sp., Nummulites sp., and Lepidocyclina sp. Above the lower Miocene is 100 m of organogenic limestone containing algae, gastropods, echinoderms, ostiucuds. miliolids, Amphisonis sp., Archaias sp.. Amphistegina sp., Gypsina sp., Elphidium sp., and other forms. The strata are referred tentatively to the middle Miocene.
Subcomplex 2. -Subcomplex 2 occupies the Nipe basin (Fig. 2) and the closely adjacent area. Like the Cauto hasin, it is deep, and is characterized by a thick section of pelagic sedimentary rocks from the base of the Miocene to the late middle t)r late Miocene. The section is better understood if described from base to top, by age.
1. The early Miocene strata are of two facies, a pelagic facies which fills the basin proper and a neritic cover on the pre-Neogene structures of the orthogeosyncline that surround the basin. The upper, or neritic, sequence can be correlated with the Lepidocy-clina-Heterostegina-Miogypsina and Miogypsi-«a-Soritiidae zones, and possibly with the lower part of the Soritiidae-Miliolidac-Amphistegi-nidae zone. The strata are organogenic, massive, recrystallized limestone, about 50-70 m thick. The most typical fossils include Neorotalia sp., Amphistegina angulata, Gypsina globulus, Nummuliles spp., Archaias angulatus, Glohige-rinoides diniiniila. Miogypsina antillea, Lepidocyclina favosa, I., iindosa, L. yurnagunensis. Carpenleria sp.. Itelerostegina sp., miliolids, algae, and corals. The rocks are widespread west of the cit\ of Bancs
"Lavanderas No. ], Cuban Stanolind Oil Co., TD 1,676 m, abandoned in Marcli 19.')8; Manzanillo No. 1, Cia. Petrolcra Tian^-Ciiha, S.A., TD 2,089 ra, abandoned in Julv t'*''6
Principal Characteristics of Cuban Neogene Stratigraphy 1951
The pelagic facies consists of shaly marl with Amphistegina angulata, Globigerinoides hisphaericus, G. ruber, Globoquadrina altispira. G. tripartita rohri, and G. venezuelana of the Globigerinoides altiaperturus—G. bisphaericiis zone. Also present are Cataphydrax dissimilis. Globoquadrina venezuelana, G. tripartita rohri, Globigerina ouachitaensis, G. praehulloides, and G. concinna angustiumbilicata of the Ca-tapsydrax dissimilis zone. The upper part of the lower Miocene also is present, as the following microfauna indicates: Orbulina sp., Candorbu-lina cf. glomerosa circularis, Glohorotalia fohsi S.I., NummuUtes cojimarensis, Paraspiroclypeus chawneri, Globigerinoides sp., and other fauna of the Glohorotalia fohsi s.l. zone.
2. The middle Miocene rocks differ litholog-ically and in facies from all other middle Miocene strata of Cuba. They consist of pelagic marl and sandy marl with Orbulina universa. Candorhulina sp., "Sphaeroidinellopsis" suhde-hiscens, "Sphaeroidinella" grimsdalei, Glohorotalia menardii, G. cf. acostaensis, G. mayeri, Globigerina decoraperta, G. trilocularis, G. apertura, G. cf. winkleri, Globoquadrina len-guaensis, Globigerinoides sacculifer, G. ruber, Amphistegina lessonii, Kuphus sp., corals, moi-lusks, and other forms. This section may extend into the upper Miocene as indicated by the presence in one sample of Orbulina universa, Globigerina decoraperta, Globoquadrina altispira, G. dehiscens, Glohorotalia crassafor-mis, Globigerinoides inmaturus, G. ruber, G. trilobus, and "Sphaeroidinella" seininulina.
3. The upper Miocene is a sequence of organogenic limestone, 70 m thick, lying above the middle Miocene strata just described; the age assignment is tentative. The fauna consists of Amphistegina angulata, A. rotundata, Gyp-sina globulus, Amphisorus sp., Sorites sp., Ar-chaias angulatus, miliolids, mollusks, and algae.
Subcomplex 3.—Subcomplex 3 occupies the Guantanamo basin (Fig. 2) and nearby areas. I have not visited the region, and data are sparse. A partial description was published by Lewis and Straczek (1955). The only samples studied at INRH were sent by Jorge Cobiella of the Department of General Geology and Paleontology, University of Oriente, Santiago de Cuba. They are from the La Cruz Formation, which consists of sandstone, conglomerate, sandy marl, and organogenic limestone with mollusks, corals, Lithophyllum sp., Amphisorus sp., Amphistegina angulata, A. rotundata, Archaias sp., Gypsina sp., and Globigerina sp. The specimens do not permit a precise age
identification. Some additional information has been published on the region by Bermudez (1961) and Charlton de Rivero (1963) under the headings " l a Cm/, [ ormation" and "Punta Maisi Formation.
T E C T O N I C S
Few general works have been published on the tectonics of the Cuban Neogene. The most useful are those by Furrazola et al. (1964) and Pushcharovskiy et al. (1967). Even those two groups of authors differed on the position of the boundary between the Oligocene and Miocene. Furrazola et al. included the Aquitanian stage within the Oligocene—a decision which greatly simplifies their descriptions of the Neogene. Pushcharovskiy et al. placed both the Oligocene and Miocene into a single tectonic cycle, but failed to indicate whether they place the Aquitanian in the Miocene or in the Oligocene. As a result, the descriptions of Neogene tectonics by those authors must be considered tentative. In general, they considered the Neogene rocks to be nmch simpler tectonically than they really arc.
A new synthesis ot the Neogene—including the Aquitanian—is presented here. The strata can be divided into three types according to tectonic stvie: f l ) transgressive cover rocks, (2) transgressive-rcgressive strata of deep, subsiding basins, and (3) transgressive deposits of shallow neritic basins
Type 1. Transgressive Cover Rocks
The transgressive cover rocks are composed of thin carbonate sequences of different ages; in some areas the age cannot be determined because of deep weathering. The strata cover transgressivelv the pre-Neogene structures of the orthogeosyncline. (ienerally they are flat lying, though locally they may be somewhat folded; the degree of folding depends on the tectonic stability of the structures covered. The rocks are of neritic facies and are present in all parts of the island.
Type 2. Transgressive-Regressive Strata of Deep, Subsiding Basins
These sedimentary rocks include marl, limestone, and sandstone, in order of abundance, from base to top. The thicknesses are greater than those of the Neogene strata of other tectonic environments Thicknesses up to 1,000-1,500 m are found in some localities. Within type 2 areas are lithofacies complex II and most of complex \ ' Nipe and Cauto basins).
1952 Manuel A. Iturralde-Vinent
Lithofacies complex II belongs to type 2 because it accumulated in a subsiding, graben-type basin between two steep faults. Uplift along the faults at the end of Oligocene time raised the areas where lithofacies complexes I, III, and IV were deposited. Evidence for the grabenlike subsidence of the area of lithofacies complex II is listed.
1. Oligocene strata of pelagic, deep-water deposition are present but do not crop out in lithofacies complex II; they are exposed mainly in complex IV.
2. The thickness of the Neogene of lithofacies complex II is about 1,000 to 1,500 m, but in lithofacies complex IV, subcomplex 1, only 300 m.
3. The early Miocene strata of lithofacies complex II are of pelagic, deep-water deposition, whereas those of the surrounding areas were formed in shallow neritic water.
4. Late Miocene and Pliocene rocks arc present in the graben area, but are absent on the surrounding blocks.
5. In the adjacent blocks of lithofacies complexes I and IV, the Oligocene is largely a pelagic, deep-water section and the entire Miocene is a shallow-water neritic sequence. Thus, at the Oligocene-Miocene boundary there is a pronounced facies discordance which has no counterpart in the area underlain by facies complex II, where Oligocene and early Miocene rocks are of the same deep-water facies.
6. Uplift of the blocks surrounding the area of lithofacies complex II is shown also by the presence of early Miocene basal conglomerate in the area of lithofacies complex I, in the section south of the Sierra tie Trinidad (lithofacies complex IV), and in subcomplex I of lithofacies complex IV.
7. Sublatitudinal folds and fractures are present in the Neogene rocks along the boundary area between lithofacies complexes II and IV.
I conclude that the area of lithofacies complex II remained depressed as the rest of the island was elevated gradually from Paleogene through early Neogene time. However, by middle Miocene time, the graben had stabilized, as shown by the fact that the facies of the middle Miocene of complexes I, II, and IV are similar. Nevertheless, the block was somewhat depressed along its northern and southern margins, because late Miocene strata were deposited in those two areas. After Miocene time, the entire block rose above sea level until middle to late Pliocene time, when deposition again occurred on both the north and south sides of the block. This fact indicates that the Miocene was a time of regression, whereas the late Pliocene was an epoch of brief transgression.
During the uplift at the end of the Miocene, the Miocene strata were folded throughout the island. Dips locally are as steep as 30-40° in the vicinity of rejuvenated pre-Neogene structures of the orthogeosyncline. Much faulting and shearing occurred, particularly along the
fault separating complexes II and IV, as well as along the flanks of some orthogeosynclinal structures.
Folds m the Neogene strata have rather broad dimensions, although small-scale structures are common throughout the island. The large-scale folds are in the Neogene basins, whereas the small-scale structures are in the vicinity of the older rejuvenated pre-Neogene structures.
Furrazola et al. (1964) indicated that the Miocene strata are discordant on all older beds (they were referring to the base of the Burdigalian, and not to the base of the Aquitanian); that conclusion is incorrect (Iturralde, 1966). Furrazola et al. generally are correct, but not with regard to the graben area of lithofacies complex II. In the areas next to the pre-Neogene structures, Burdigalian rocks in places overlie early Eocene rocks. However, within the graben, farthest frotn the ancient structures of the blocks which bound lithofacies complex IT, the basal Neogene and not the Burdigalian strata directly overlie the Oligocene with facies and lithologic conformity, thus, in the graben, the Burdigalian is concordant in all respects upon the Aquitanian.
The other principal unconformities are at the top of the middle Miocene, the top of the upper Miocene, and at the top of the Pliocene, Locally, unconformities of less importance are present, e.i;.. between Aquitanian and Burdigalian strata and between Burdigalian and Vindo-bonian strata.
Lithofacies complex I also is included in this type, but as a subtvpe in which the entire sequence is neritic. At the base, the sequence is transgressive, but grades upward into a less regressive type. The area was uplifted at the end of the Paleogene (at least the northern margin): after Burdigalian time, it subsided considerably during the remainder o( early to middle Miocene time.
The Cauto and Nipe subcomplexes of lithofacies complex V also were deposited in a deep-basin structural environment. Pelagic beds characterize the lower part of the section and grade upward into shallow neritic beds. There are, however, certain differences in history between these subcomplexes and lithofacies complex II: (1) the presence of boundary graben faults has not been proved in the Cauto and Nipe basins, (2) in these two basins, sandy beds are absent at the top of the sequences, and (3) the presence of Pliocene has not been proved in either the C auto or Nipe basin.
Principal Characteristics of Cuban Neogene Stratigraphy 1953
Type 3. Transgressive Deposits of Shallow Neritic Basins
Strata of type 3 are developed the most widely within the eugeosynclinal province. They include lithofacies complexes III, IV, and the Guantanamo basin of lithofacies complex V. The rocks consist of a carbonate and terrigenous-clastic sequence of neritic deposition. The strata commonly overlap pre-Oligo-cene rocks.
Generally sequences of type 3 areas show a mildly regressive character. There was a gradual shallowing of seawater during their deposition. Most type 3 areas were uplifted near the end of middle Miocene time and were never again covered by the sea.
The gradual uplift of type 3 areas produced milder tectonic effects than those which affected the Neogene of the type 2 areas. Broad, very gentle folding occurred in type 3 areas.
EARLY MIOCENE
MIDDLE MIOCENE
FIG. 13.—Paleogeographic reconstruction of Cuba during Neogene. /, carbonate rocks, neritic facies; 2, marly rocks, pelagic facies; 3, shale rocks, shallow-water brackish facies; 4, sandy terrigenous rocks; 5, basal conglomerate; 6, land areas; 7, faults.
1954 Manuel A. Iturralde-Vinent
and in only a very few places do dips exceed 15-20°. The steepest dips are adjacent to old structures within the eugeosynclinal section. The overall dip is toward the sea on all sides of the island. Furrazola et al. (1964) have described steeper dips (up to 80° in one place) in the strata of this structural type, but they are related to salt diapirism in northwestern Camagiiey Province (Meyerhoff and Hatten. 1968). The salt diapirs are mainly in the area of the Cretaceous miogeosyncline, not in the eugeosynclinal part of Cuba.
Deep crustal faults are less common in the type 3 than in the type 2 areas. Where present, such faults generally are associated with pre-Neogene structures. The principal discordances within the Neogene section of this tectonic setting are at the base of the Neogene and at the top of the middle Miocene.
Conclusions
Generally, the Neogene tectonic cycle is structurally simple. It is characterized by atypical transgressive and regressive sequences, except in lithofacies complex II, where the overall succession shows a typical regressive character. The principal discordances are at the base of the Neogene (base of Aquitanian), except in the deep-basin area of Uthofacies complex II and at the top of the middle Miocene. The development of active wrench faults during Neogene time has not been established. Consequently, block-type faulting seems to have predominated.
PALEOGEOGHAPHY
Except for the paleogeographic maps of Furrazola et al. (1964) and Weyl (1966a, b ) , no paleogeographic reconstructions of the Cuban Neogene are available. The paleogeogra-phy is summarized in three steps in Figure 13.
Tectonic movements at the end of Paleogene time led to the development of the sublatitudi-nal faults bounding lithofacies complex II. Except for the area of that complex, all of the island was exposed. Shortly thereafter, at the beginning of early Miocene time, the sea transgressed much of Cuba.
Early Miocene rocks are characterized by sharp faciologic differentiation of the lithofacies complexes. Shallow-water beds are found in certain areas, and deep-water beds in others. During the middle Miocene, water depths across the island were about the same as during early Miocene, and deep pelagic basins disappeared except on the Zapata Peninsula and
in the Nipe basin. Elsewhere, faciologic "homo-genization" occurred and shallow-water deposition predominated. At the end of the middle Miocene time, all of the island emerged except the Zapata Peninsula, northernmost Matanzas Province, and parts of Oriente. Most of the folding of Miocene rocks occurred at that time, forming folds that parallel the axial trend of the island. During late Miocene time, complete emergence occurred.
Minor transgressions occurred in northern Matanzas, on the Zapata Peninsula, and possibly in parts of Oriente Province during late Pliocene time. The sea was shallow, and deposition was near-continental in some areas. Generally the Neogene terminated with complete emergence of Cuba, uphft of major mountain ranges, and activit) on several deep crustal faults, such as those hounding Bartlett Trough.
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